block: add an API to atomically update queue limits (d690cb8a) · Commits · git / linux-net

block/blk-core.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -425,6 +425,7 @@ struct request_queue *blk_alloc_queue(int node_id)
		mutex_init(&q->debugfs_mutex);
		mutex_init(&q->sysfs_lock);
		mutex_init(&q->sysfs_dir_lock);
		mutex_init(&q->limits_lock);
		mutex_init(&q->rq_qos_mutex);
		spin_lock_init(&q->queue_lock);

block/blk-settings.c

+192 −36

Original line number	Diff line number	Diff line
		@@ -25,42 +25,6 @@ void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
		}
		EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);

		/**
		* blk_set_default_limits - reset limits to default values
		* @lim: the queue_limits structure to reset
		*
		* Description:
		* Returns a queue_limit struct to its default state.
		*/
		void blk_set_default_limits(struct queue_limits *lim)
		{
		lim->max_segments = BLK_MAX_SEGMENTS;
		lim->max_discard_segments = 1;
		lim->max_integrity_segments = 0;
		lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
		lim->virt_boundary_mask = 0;
		lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
		lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
		lim->max_user_sectors = lim->max_dev_sectors = 0;
		lim->chunk_sectors = 0;
		lim->max_write_zeroes_sectors = 0;
		lim->max_zone_append_sectors = 0;
		lim->max_discard_sectors = 0;
		lim->max_hw_discard_sectors = 0;
		lim->max_secure_erase_sectors = 0;
		lim->discard_granularity = 512;
		lim->discard_alignment = 0;
		lim->discard_misaligned = 0;
		lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
		lim->bounce = BLK_BOUNCE_NONE;
		lim->alignment_offset = 0;
		lim->io_opt = 0;
		lim->misaligned = 0;
		lim->zoned = false;
		lim->zone_write_granularity = 0;
		lim->dma_alignment = 511;
		}

		/**
		* blk_set_stacking_limits - set default limits for stacking devices
		* @lim: the queue_limits structure to reset
		@@ -101,6 +65,198 @@ static void blk_apply_bdi_limits(struct backing_dev_info *bdi,
		bdi->io_pages = lim->max_sectors >> PAGE_SECTORS_SHIFT;
		}

		static int blk_validate_zoned_limits(struct queue_limits *lim)
		{
		if (!lim->zoned) {
		if (WARN_ON_ONCE(lim->max_open_zones) \|\|
		WARN_ON_ONCE(lim->max_active_zones) \|\|
		WARN_ON_ONCE(lim->zone_write_granularity) \|\|
		WARN_ON_ONCE(lim->max_zone_append_sectors))
		return -EINVAL;
		return 0;
		}

		if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_BLK_DEV_ZONED)))
		return -EINVAL;

		if (lim->zone_write_granularity < lim->logical_block_size)
		lim->zone_write_granularity = lim->logical_block_size;

		if (lim->max_zone_append_sectors) {
		/*
		* The Zone Append size is limited by the maximum I/O size
		* and the zone size given that it can't span zones.
		*/
		lim->max_zone_append_sectors =
		min3(lim->max_hw_sectors,
		lim->max_zone_append_sectors,
		lim->chunk_sectors);
		}

		return 0;
		}

		/*
		* Check that the limits in lim are valid, initialize defaults for unset
		* values, and cap values based on others where needed.
		*/
		static int blk_validate_limits(struct queue_limits *lim)
		{
		unsigned int max_hw_sectors;

		/*
		* Unless otherwise specified, default to 512 byte logical blocks and a
		* physical block size equal to the logical block size.
		*/
		if (!lim->logical_block_size)
		lim->logical_block_size = SECTOR_SIZE;
		if (lim->physical_block_size < lim->logical_block_size)
		lim->physical_block_size = lim->logical_block_size;

		/*
		* The minimum I/O size defaults to the physical block size unless
		* explicitly overridden.
		*/
		if (lim->io_min < lim->physical_block_size)
		lim->io_min = lim->physical_block_size;

		/*
		* max_hw_sectors has a somewhat weird default for historical reason,
		* but driver really should set their own instead of relying on this
		* value.
		*
		* The block layer relies on the fact that every driver can
		* handle at lest a page worth of data per I/O, and needs the value
		* aligned to the logical block size.
		*/
		if (!lim->max_hw_sectors)
		lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
		if (WARN_ON_ONCE(lim->max_hw_sectors < PAGE_SECTORS))
		return -EINVAL;
		lim->max_hw_sectors = round_down(lim->max_hw_sectors,
		lim->logical_block_size >> SECTOR_SHIFT);

		/*
		* The actual max_sectors value is a complex beast and also takes the
		* max_dev_sectors value (set by SCSI ULPs) and a user configurable
		* value into account. The ->max_sectors value is always calculated
		* from these, so directly setting it won't have any effect.
		*/
		max_hw_sectors = min_not_zero(lim->max_hw_sectors,
		lim->max_dev_sectors);
		if (lim->max_user_sectors) {
		if (lim->max_user_sectors > max_hw_sectors \|\|
		lim->max_user_sectors < PAGE_SIZE / SECTOR_SIZE)
		return -EINVAL;
		lim->max_sectors = min(max_hw_sectors, lim->max_user_sectors);
		} else {
		lim->max_sectors = min(max_hw_sectors, BLK_DEF_MAX_SECTORS_CAP);
		}
		lim->max_sectors = round_down(lim->max_sectors,
		lim->logical_block_size >> SECTOR_SHIFT);

		/*
		* Random default for the maximum number of segments. Driver should not
		* rely on this and set their own.
		*/
		if (!lim->max_segments)
		lim->max_segments = BLK_MAX_SEGMENTS;

		lim->max_discard_sectors = lim->max_hw_discard_sectors;
		if (!lim->max_discard_segments)
		lim->max_discard_segments = 1;

		if (lim->discard_granularity < lim->physical_block_size)
		lim->discard_granularity = lim->physical_block_size;

		/*
		* By default there is no limit on the segment boundary alignment,
		* but if there is one it can't be smaller than the page size as
		* that would break all the normal I/O patterns.
		*/
		if (!lim->seg_boundary_mask)
		lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
		if (WARN_ON_ONCE(lim->seg_boundary_mask < PAGE_SIZE - 1))
		return -EINVAL;

		/*
		* The maximum segment size has an odd historic 64k default that
		* drivers probably should override. Just like the I/O size we
		* require drivers to at least handle a full page per segment.
		*/
		if (!lim->max_segment_size)
		lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
		if (WARN_ON_ONCE(lim->max_segment_size < PAGE_SIZE))
		return -EINVAL;

		/*
		* Devices that require a virtual boundary do not support scatter/gather
		* I/O natively, but instead require a descriptor list entry for each
		* page (which might not be identical to the Linux PAGE_SIZE). Because
		* of that they are not limited by our notion of "segment size".
		*/
		if (lim->virt_boundary_mask) {
		if (WARN_ON_ONCE(lim->max_segment_size &&
		lim->max_segment_size != UINT_MAX))
		return -EINVAL;
		lim->max_segment_size = UINT_MAX;
		}

		/*
		* We require drivers to at least do logical block aligned I/O, but
		* historically could not check for that due to the separate calls
		* to set the limits. Once the transition is finished the check
		* below should be narrowed down to check the logical block size.
		*/
		if (!lim->dma_alignment)
		lim->dma_alignment = SECTOR_SIZE - 1;
		if (WARN_ON_ONCE(lim->dma_alignment > PAGE_SIZE))
		return -EINVAL;

		if (lim->alignment_offset) {
		lim->alignment_offset &= (lim->physical_block_size - 1);
		lim->misaligned = 0;
		}

		return blk_validate_zoned_limits(lim);
		}

		/*
		* Set the default limits for a newly allocated queue. @lim contains the
		* initial limits set by the driver, which could be no limit in which case
		* all fields are cleared to zero.
		*/
		int blk_set_default_limits(struct queue_limits *lim)
		{
		return blk_validate_limits(lim);
		}

		/**
		* queue_limits_commit_update - commit an atomic update of queue limits
		* @q: queue to update
		* @lim: limits to apply
		*
		* Apply the limits in @lim that were obtained from queue_limits_start_update()
		* and updated by the caller to @q.
		*
		* Returns 0 if successful, else a negative error code.
		*/
		int queue_limits_commit_update(struct request_queue *q,
		struct queue_limits *lim)
		__releases(q->limits_lock)
		{
		int error = blk_validate_limits(lim);

		if (!error) {
		q->limits = *lim;
		if (q->disk)
		blk_apply_bdi_limits(q->disk->bdi, lim);
		}
		mutex_unlock(&q->limits_lock);
		return error;
		}
		EXPORT_SYMBOL_GPL(queue_limits_commit_update);

		/**
		* blk_queue_bounce_limit - set bounce buffer limit for queue
		* @q: the request queue for the device

block/blk.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -330,7 +330,7 @@ void blk_rq_set_mixed_merge(struct request *rq);
		bool blk_rq_merge_ok(struct request rq, struct bio bio);
		enum elv_merge blk_try_merge(struct request rq, struct bio bio);

		void blk_set_default_limits(struct queue_limits *lim);
		int blk_set_default_limits(struct queue_limits *lim);
		int blk_dev_init(void);

		/*

include/linux/blkdev.h

+23 −0

Original line number	Diff line number	Diff line
		@@ -474,6 +474,7 @@ struct request_queue {

		struct mutex sysfs_lock;
		struct mutex sysfs_dir_lock;
		struct mutex limits_lock;

		/*
		* for reusing dead hctx instance in case of updating
		@@ -862,6 +863,28 @@ static inline unsigned int blk_chunk_sectors_left(sector_t offset,
		return chunk_sectors - (offset & (chunk_sectors - 1));
		}

		/**
		* queue_limits_start_update - start an atomic update of queue limits
		* @q: queue to update
		*
		* This functions starts an atomic update of the queue limits. It takes a lock
		* to prevent other updates and returns a snapshot of the current limits that
		* the caller can modify. The caller must call queue_limits_commit_update()
		* to finish the update.
		*
		* Context: process context. The caller must have frozen the queue or ensured
		* that there is outstanding I/O by other means.
		*/
		static inline struct queue_limits
		queue_limits_start_update(struct request_queue *q)
		__acquires(q->limits_lock)
		{
		mutex_lock(&q->limits_lock);
		return q->limits;
		}
		int queue_limits_commit_update(struct request_queue *q,
		struct queue_limits *lim);

		/*
		* Access functions for manipulating queue properties
		*/